THE ABDOMEN 845 



iliac articulation on a level wnth the pel vac brim, where it joins 

 the external iliac, and so the common iliac vein is formed. In its 

 course it lies behind the corresponding artery. There are no valves 

 in the vein itself, but its branches are freely provided with them. 



The internal iliac vein is developed from the lower part of the cardinal 

 vein. 



Internal Iliac Lymphatic Glands. — These glands are about ten in 

 number, and are associated with the origins of the branches of the 

 internal iliac arter}^ One of them lies near the side of the rectum, 

 in relation with the middle haemorrhoidal artery, and is spoken of 

 as the middle hcemorrhoidal gland. 



The afferent vessels of the internal iliac glands return lymph from 

 the parts supplied by the branches of the internal iliac artery. 

 Thus, they receive afferent vessels from the following parts; 



1. Upper part of the anal canal, above the anal valves. 



2. Lower part of the rectum. 



3. Bladder. 



4. Vesicular seminalis and vas deferens. 



5. Prostate gland. 



6. Prostatic, membranous, and bulbar portions of the urethra, 

 in part. 



7. Uterus (cer\4x). 



8. Vagina (central part). 



9. Deep structures of gluteal region, supplied by gluteal artery. 



10. Deep structures of upper part of back of thigh, supplied by 

 sciatic artery. 



11. Deep structures of perineum. 



The efferent vessels of the internal iliac glands pass to the posterior 

 group of common iliac glands. 



Anterior Primary Divisions of the Sacral and Coccygeal Nerves. 

 — ^There are five sacral nerves and one coccygeal nerve on either 

 side. The anterior primary divisions of the first four sacral nerves 

 emerge into the pelvis through the anterior sacral foramina, and 

 that of the fifth sacral passes between the inferior lateral angle 

 of the sacrum and the transverse process of the first coccygeal 

 vertebra, through the coccygeus muscle. The anterior primary 

 division of the coccygeal nerve enters the pelvis below the trans- 

 verse process of the first coccygeal vertebra, through the coccy- 

 geus muscle. The first and second sacral nerves are of large size, 

 and their course is obliquely downwards and outwards. Beyond 

 the second they diminish rapidly in size, and pass more horizontally. 

 They receive grey rami communicantes from the adjacent ganglia 

 of the pelvic sympathetic cord, and the third and fourth nerves 

 (sometimes also the second) furnish white rami communicantes to 

 the corresponding pelvic plexus. The anterior primary divisions 

 of the first and second sacral nerves divide each into an anterior 

 or ventral and a posterior or dorsal branch. The anterior primary 

 division of the third sacral nerve divides into an upper and a lower 



